Java methods

Java methods

Methods represents business logic of application and it  defined inside class.
Ex: I have java class ,in that class I want to do add two numbers so we should keep this logic of addition in methods.
  • Method should have a signature and signature represents method name and parameters.
  • A java class contain multiple methods.
syntax
<access modifier> <return type> <method_Name>(parameters){
//method body
//business code

}
Access modifiers for  methods:
Access modifiers  applicable to methods are  public,private to  check visibility of methods to other classes.
Return type:
Return type is  the data type of the value returned by the method,if method doesn't return value ,return type value  should be void.
Method_Name:
Method name is any legal identifier.
Parameters:
Parameters should placed in parenthesis() by keeping(;).if there is no parameters ,we must use use empty parameters.
Naming a method
Method name is any legal identifier. method name should be the verb in lower case.if there is multi-word method name that begins with lowercase and first letter of each second word must capital letter.
How to invoke methods?
In java we have two types of methods 
  • Instance methods
  • Static methods
Instance methods:
Instance methods are  invoked by using Object reference  a class.
package com.practice;
public class Instance_Method_Demo {
int x = 30;// instance variable declaration
int y = 30;// instance variable declaration
// instance method
public void add() {
System.out.println("sum of numbers:" + (x + y));

}
public static void main(String[] args) {
// Object creation
Instance_Method_Demo instance_Method_Demo = new Instance_Method_Demo();
instance_Method_Demo.add();// invoking instance method with object
// reference
}

}
output
sum of numbers:60
Static methods:
Static methods are invoked by using class name like below
<classname>.<static_method>
Example
package com.practice;
public class Static_Method_Demo {
static int x = 30;// static variable declaration
static int y = 30;// static variable declaration

// static method
public static void add() {
System.out.println("sum of numbers:" + (x + y));

}

public static void main(String[] args) {
// invoking static method by using class name
Static_Method_Demo.add();
}

}
output
sum of numbers:60
Example  for method with parameters
package com.practice;

public class Static_Method_Demo {
static int x;// static variable declaration
static int y;// static variable declaration

// static method
public static void add(int x,int y) {
System.out.println("sum of numbers:" + (x + y));

}

public static void main(String[] args) {
// invoking static method by using class name
Static_Method_Demo.add(30,30);
}

}
output
sum of numbers:60
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